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					Medical Micro Block #3 – 1996                                                                                                      1
                                                        MEDICAL MICROBIOLOGY
                                                           EXAMINATION #3
                                                            December 11, 1996

1. Mycobacterium tuberculosis is:
    A. Gram-negative
    B. Killed by specific antibody and complement
    C. An obligate aerobe
    D. A rapid grower
    E. Gram-positive

2. Which of the following characteristics can be accounted for by the high lipid content of Mycobacterium tuberculosis' cell
    A. Their relative impermeability to stains
    B. Their acid fastness
    C. Their unusual resistance to killing by acid and alkali
    D. Their resistance to bactericidal activity of antibody and complement
    E. All of the above

3. In tuberculosis, the healed and frequently calcified primary complex lesions which can be seen in chest radiographs, are
referred to as:
     A. Tubercles
     B. Miliary TB
     C. The Ghon complex
     D. Reactivation TB
     E. Serpentine cords

4. The lipid that is responsible for the serpentine formation in Mycobacterium tuberculosis is:
    A. Wax D
    B. Mycolic acid
    C. Cord factor
    D. Lipid A
    E. Sulfatide

5. Mycobacterium leprae differs from Mycobacterium tuberculosis in that:
    A. M. tuberculosis can be grown in vitro while M. leprae cannot
    B. M. leprae is gram-negative while M. tuberculosis is gram-positive
    C. M. leprae causes chronic granulomatis lesions while M. tuberculosis does not
    D. M. leprae can live inside normal macrophages while M. tuberculosis cannot
    E. M. leprae can be killed by antibiotics where as M. tuberculosis cannot

The following questions deal with the "Achey Amoeba" case history.

An 18 year old healthy male had noted fatigue and some generalized muscle aches for several days. He awoke on the morning of
October 31 (which he distinctly remembered as he had been planning to go to a Halloween Ball as an amoeba) feeling chilly and
suffering from a sore throat and a severe frontal headache. He also felt hot, and recorded a temperature of 102oF. Over the next
several days he became increasingly bothered by a persistent non- productive cough, along with his headache and fever. He also noted
increasing severity of muscle aches and pains. On November 2, he complained of a severe left ear
ache, and next day he consulted a physician.

6. Your differential diagnosis, at this point, would include which of the following?
    A. Meningitis, strep" throat, flu, pneumococcal pneumonia,Legionairre's disease
    B. Mycoplasma pneumonia, Rocky Mountain spotted fever,shigellosis
    C. "Walking" pneumonia, botulism, otitis media, psittacosis
    D. Mycoplasma pneumonia, "strep" throat, flu, Chlamydial pneumonia, otitis media
    E. Syphillis, gonorrhea, tetanus, dysentery, otitis media

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The doctor determined that the young man lived alone and had no pets. He did not smoke and only very occasionally drank alcohol.
He had a girlfriend with whom he had a monogamous relationship.

7. The young man's age, and the fact that he did not smoke or drink would tend to rule out which of the following?
    A. Legionnaire's disease
    B. Strep throat
    C. Influenza
    D. Mycoplasma pneumonia
    E. Otitis media

The patient looked reasonably well but was obviously in pain because of the ear ache and the distressing and persistent dry
cough. The left tympanic membrane was slightly erythematous. A single tender enlarged cervical lymph node was palpable
below the left ear lobe. His hematocrit was normal. His leucocyte count was 8000 cells per cubic millimeter with a normal differential.
No beta hemolytic colonies from the throat culture grew on blood agar.

8. The lack of beta-hemolytic colonies from the throat culture indicates:
    A. He does not have influenza, as the flu virus produces beta-hemolytic colonies on blood agar.
    B. He does not have otitis media caused by H. influenzae.
    C. He does not have a sore throat caused by Streptococcus pyogenes.
    D. He does not have Mycoplasma pneumonia.
    E. He does not have Legionellosis.

Examination of the chest revealed crackling inspiratory rales over the right lower lungfield posteriorly. X-ray showed a stringy, poorly
delineated infiltrate in the most posterior and inferior segment of the right lower lobe. A satisfactory sputum sample could not be

9. How does this X-ray differ from what would be seen with pneumococcal pneumonia?
    A. The position of the infiltrate would be different.
    B. There would likely be more consolidation with pneumococcal pneumonia.
    C. The infiltrate would be only interstitial in pneumococcal pneumonia.
    D. It is always bilateral in pneumococcal pneumonia.

10. Penicillin would not work in this disease because:
    A. The organism produces a beta-lactamase
    B. The organism produces a beta -hemolysin
    C. The organism makes fried egg colonies
    D. The organism has no cell wall
    E. The organism has sterols in its cell membrane

11. Where did the young man acquire the Mycoplasma?
    A. Via sexual contact
    B. From his normal flora
    C. At the blood bank when he gave blood
    D. From someone else with the disease via the respiratory route
    E. From unpasteurized milk

12. The bacterium that causes Epidemic louse-borne typhus is:
    A. Rickettsia prowazekii
    B. Rickettsia typhi
    C. Rickettsia mooseri
    D. Rickettsia richettsii
    E. Rickettsia akari

13. Which of the following organisms is unusually stable outside of host cells?
    A. Rikhettsia prowazekii
    B. Rickettsia akari
    C. Rickettsia mooseri
    D. Coxiella burnettii
    E. Rickettsia canada

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Medical Micro Block #3 – 1996                                                                                                       3
14. Chlamydia trachomatis produces which of the following diseases?
    A. Trachoma
    B. Inclusion conjunctivitis
    C. Lymphogranuloma venereum
    D. Nonspecific urethritis
    E. All of the above

15. Which of the following bacteria employs two distinct morphological forms
to infect cells?
     A. Rickettsia prowazekii
     B. Streptococcus pneumoniae
     C. Staphylococcus aureus
     D. Chlamydia psittaci
     E. Escherichia coli

16. Transient, usually asymptomatic, bacteremias can occur as a result of dental manipulation. Antibiotic prophylaxis would be
recommended in each of the following cases EXCEPT:
    A. Congenital cardiovascular defect
    B. Previous episode of bacterial endocarditis
    C. Damage to the heart by rheumatic fever (rheumatic heart disease)
    D. Myocardial infarction
    E. Mitral valve replacement

17. The microorganism believed to be chiefly responsible for dental caries is:
    A. Streptococcus mutans
    B. Lactobacillus acidophilus
    C. Haemophilus influenzae
    D. Bacteroides intermedius
    E. Stretococcus pyogenes

18. Hyperbaric oxygen therapy is potentially beneficial in the clinical management of necrotizing soft tissue infection.
    A. True
    B. False

19. Clostridium tetani is a significant cause of clostridial soft tissue gangrene.
    A. True
    B. False

20. Necrotizing soft tisse infections due to "flesh eating" Group A beta-hemolytic streptococci are always polymicrobial (involve
multiple types of bacterial flora).
    A. True
    B. False

21. Which of the following statements regarding nosocomial infections is TRUE?
    A. Nosocomial respiratory infections are the most common nosocomial infection in general hospitals.
    B. Enterococci are the most common organisms causing nosocomial bacteremia.
    C. Nosocomial urinary tract infections have the highest mortality of all nosocomial infections from any site.
    D. Empirical use of broad-spectrum antibiotics for prophylaxis of most nosocomial intections is contraindicated.
    E. Most nosocomial pneumonias are caused by Streptocococcus pneumoniae.

22. The MOST likely cause of a surgical wound infection within 24 hours of surgery is:
    A. Staphylococcus aureus
    B. Candida species
    C. Group A Streptococci
    D. E. coli
    E. Pseudomonas aeruginosa

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23. Authoritative guidance on sexually transmitted diseases can be obtained from (if you know the sources, you know the
    A. MHA-TP
    C. OSHA
    D. STP
    E. TMA

24. Physicians must report which one of the following diseases:
    A. Chancroid
    B. Chlamydia
    C. Herpes simplex
    D. LGV
    E. Scabies

25. You have decided that your patient's sexual behavior puts her/him at risk for gonorrhea. For what other disease should you also
screen this patient because it has a higher prevalence than gonorrhea?
    A. Chlamydia
    B. Hepatitis B
    C. HIV
    D. Molluscum contagiosum
    E. Syphillis

26. Acquired Immunodeficiency Syndrome can last as long as:
    A. Decades
    B. Years
    C. Months
    D. Weeks
    E. Days

27. Controlling the incidence of Human Immunodeficiency Virus (HIV-1) in a
community depends on:
    A. Education
    B. Quarantine
    C. Screening
    D. Treatment
    C. Vaccination

29. All of the following statements about Calymmatobacterium granulomatis are true EXCEPT:
    A. It is a Gram-negative bacterium
    B. The disease it produces is called Donovanosis
    C. The disease it produces in humans is sexually transmitted
    D. Biopsy of skin lesions may be useful in diagnosis
    E. It is transmitted by the sand fly

30. Which microorganism(s) CANNOT grow in the complete absence of
    A. Facultative anaerobes
    B. Strict anaerobes
    C. Both
    D. Neither

31. A patient who had suffered a severe blow to the face resulting in loss of a molar tooth subsequently developed, on the buccal
mucosa, a granulomatous lesion which formed a draining abscess to the outside surface of the cheek. The draining pus was found to
contain small yellowish "granules". Which of the following would be the predominate finding in a gram stained film of draining pus?
    A. Budding yeast cells
    B. Gram positive branched filamentous rods
    C. Gram negative fusiform bacilli and spirochetes
    D. Mixed gram negative rods, cocci and yeasts
    E. Gram positive streptococci
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32. Your patient is a 70-year-old man who underwent bowel surgery for colon cancer 3 days ago. He now has a fever and abdominal
pain. You are concerned that he may have peritonitis. Which one of the following pairs of organisms is MOST likely to be the cause:
    A. Bacteroides fragilis and Escherichia coli
    B. Bordetella pertussis and Salmonella enteritidis
    C. Actinomyces israelii and Campylobacter jejuni
    D. Clostridium botulinum and Shigella dysenteriae

33. "Tetanus neonatorum":
     A. Is caused by placental passage of Clostridium tetani into the neonates circulatory system
     B. Is caused by failure of protective antibodies to cross the placenta
     C. Usually results from infection of the umbilicus by Clostridium tetani
     D. Is caused by placental passage of tetanospasmin into the neonate's circulatory system
     E. Two of the above answers are correct

34. Which organism(s) produces enzymes or toxins that cause tissue necrosis?
    A. Clostridium botulinum
    B. Clostridium perfringens
    C. Both of the above microorganisms
    D. Neither of the above microorganisms

35. Five days ago a 65-year-old woman with a lower urinary tract infection began taking ampicillin. She now has fever and severe
diarrhea. Of the organisms listed, which one is MOST likely to be the cause of the diarrhea?
     A. Clostridium difficile
     B. Bacteroides fragilis
     C. Proteus mirabilis
     D. Bordetella pertussis
     E. Clostridium perfringens type A

36. A patient receiving steroid therapy developed a chronic pulmonary infection that was confirmed by X-ray. The patient reported
chest pain and weight loss. A sputum specimen showed narrow gram positive filaments. Staining and microscopic observation of the
colony showed gram positive, partially acid fast filaments. The most likely etiology of this infection was:
    A. Actinomyces israelii
    B. Streptomyces nodosus
    C. Candida albicans
    D. Nocardia asteroides
    E. Streptococcus pneumoniae

37. Appropriate antibiotic treatment for actinomycetoma:
    A. Penicillin
    B. Streptomycin
    C. Amphotericin B
    D. A and B
    E. A, B, and C

38. Fungi differ from bacteria in:
    A. Fungi are non-motile
    B. Presence of a nucleus
    C. Presence of a cell wall
    D. A and B
    E. A, B, and C

40. A skin scraping from a lesion of a patient who reported a number of light pigmented lesions of varying size on the trunk of the
body showed a mixture of round yeast cells and hyphae. The lesions were most likely
    A. Tinea corporus associated with Microsporum canis
    B. Tinea corporus associated with Malassezia furfur
    C. Pityriasis versicolor associated with Malassezia furfur
    D. Pityriasis versicolor associated with Trichosporon beigelii
    E. Tinea nigra associated with Microsporum canis

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Medical Micro Block #3 – 1996                                                                                                       6
Use the following case history to answer questions 41 and 42.

A 5 year old boy is brought in by his mother who has noted marked scaling in the scalp for the past two months. She has noted no
improvement since she started using a dandruff shampoo to wash his hair. Recently he has begun to have patches of alopecia in which
there is scaling present. On physical exam he is noted to have a 3X2 cm area of alopecia on the vertex of the scalp. Within this area
are noted "black dots" and scale. Fungal culture was positive for Trichophyton tonsurans.

41. In culture, species of Trichophyton are distinguished by:
     A. Colonial morphology and microscopic appearance of macroconidia
     B. Colonial morphology and microscopic appearance of microconidia
     C. Colonial morphology and microscopic appearance of distinctive broad-based budding yeast
     D. Colonial morphology and microscopic appearance of arthroconidia
     E. Colonial morphology and microscopic appearance of sporangia

42. Two anti-fungal treatments were prescribed. The most likely effective combination is:
    A. Oral griseofulvin and a ketoconazole shampoo
    B. Oral 5-flurocytosine and a ketoconazole shampoo
    C. Amphotericin B given IV and nystatin ointment
    D. Miconazole ointment and ketoconazole shampoo
    E. Oral ciclopirox olamine and topical nystatin

43. Anthropophilic dermatophytes:
    A. Are more likely to cause chronic disease than other dermatophytes
    B. Are more likely to cause mild disease than other dermatophytes
    C. Are more likely to have reduced sensitivity to topical treatment than other dermatophytes
    D. Are more likely to cause recurrent disease than other dermatophytes
    E. All of the above

Use the following responses to answer questions 45-47. A response may be used more than once.
A. Deep-sea fishing
B. Cleaning out a bird roost area in Tennessee
C. Joining an archeological "dig" in the desert southwest (USA)
D. Walking barefoot
E. None of the above

45. The activity that would be most likely to result in exposure to the agent(s)
of mycetoma.

46. The activity that would be most likely result in exposure to the agent(s) of

47. The activity that would most likely result in exposure to the agent(s) of

48. Thermally dimorphic fungi:
    A. Coccidioides immitis, Histoplasma capsulatum, Aspergillus fumigatus
    B. Blastomyces dermatitidis, Sporothrix schenkii, Candida albicans
    C. Paracoccidioides brasiliensis, Histoplasma capsulatum, Coccidioides immitis
    D. Sporothrix schenkii, Candida albicans, Histoplasma capsulatum
    E. Blastomyces dermatitidis, Histoplasma capsulatum, Aspergillus fumigatus

Use the following to answer questions 49-51. An answer may be used more than once.
A. Intracellular yeast cells
B. Arthroconidia or arthropores
C. Sporangia or spherules
D. Hyaline hyphae
E. A yeast with multiple buds

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Medical Micro Block #3 – 1996                                                                                                             7
49. A positive specimen from a patient suspected to have coccidioidomycosis when examined microscopically would show:

50. A positive specimen from a patient suspected to have tinea corporus when examined microscopically would show:

51. A positive specimen from a patient suspected to have paracoccidioidomycosis when examined microscopically would

52. Over the course of two weeks at a large hospital, two patients who underwent surgery to repair a complex leg fracture sustained in
an automobile accident developed a fever on the third post-surgery day. Patient A was neutropenic due to underlying disease and
treatment. Patient B had no underlying conditions. Both patients had a central venous catheter placed the day of surgery. Fever
persisted even with empirical anti-bacterial antibiotics. No bacterial agents of nosocomial infection were isolated from the
pretreatment specimens. Fungal blood cultures were negative although fungal infection was suspected. The therapy/treatment
indications for these patients would suggest that which of the following was most appropriate?
     A. Remove the catheter for both patients
     B. Remove the catheter for both patients and treat patient A with amphotericin B
     C. Remove the catheter for both patients and treat both patients with amphotericin B
     D. Remove the catheter for both patients and treat patient A with amphotericin B and patient B with fluconazole
     E. Wait to initiate treatment until a positive fungal culture is obtained.

53. Microbe(s) that show a marked tissue tropism for hematogenously disseminated disease of the central nervous system:
    A. Cryptococcus neoformans
    B. Nocardia asteroides
    C. Paracoccidioides brasiliensis and Cryptococcus neoformans
    D. Cryptococcus neoformans and Nocardia asteroides
    E. Nocardia asteroides and Histoplasma capsulatum

54. Candida albicans was isolated from sputum of a patient with pneumonia. This isolation is sufficient for a diagnosis of candidiasis:
    A. True
    B. False

Select the best answer:

56. An 8-year-old boy was tested to determine whether the rash he experienced recently was due to rubella. One serum sample was
collected 4 days after the rash appeared and a second sample was collected 14 days later. Results of a traditional rubella antibody test
(which detects primarily IgG) were as follows: sample 1=<1:10 and sample 2=1:160. What do these results indicate about the cause
of the rash?
     A. The results are inconclusive.
     B. An additional sample should be collected in one month and should be tested.
     C. The rash was due to rubella infection.
     D. The boy was immune to rubella before the rash.
     E. Possible cross reaction with rubeola

57. Consider the following rubella antibody testing results from tests for
rubella IgM and IgG:

What do these results suggest?
   A. The infant probably has a congenitally acquired rubella infection.
   B. The infant was born with something in his serum that gave false-positive results in the rubella IgM test.
   C. Post-natal infection
   D. The infant's high rubella titer at 6 months is due to maternal antibody.
   E. Results were inconclusive.

58. In a patient with conjuctivitis or keratoconjunctivitis, which of the
following viruses would be the most likely suspect?
     A. Papillomarvirus
     B. Adenovirus
     C. Variola virus
     D. Epstein-Barr virus
     E. Influenza

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Medical Micro Block #3 – 1996                                                                                                             8
59. Erythema infectiosum (fifth disease) is the name given to the clinical syndrome associated with which of the following viruses?
    A. Hepatitis B virus
    B. Varicella
    C. Molluscum contagiosum
    D. Human parvovirus B19
    E. Adenovirus

60. Which of the pairs of viruses below are members of the same family?
    A. Coxsackie A virus and hepatitis C virus
    B. Rabies and rubella
    C. Measles and mumps
    D. Influenza and parainfluenza
    E. Herpes simplex and polyomavirus

61. Which of the following statements accurately describes rabies and the rabies virus?
    A. The infection is characterized by vesicular lesions at the site of infection.
    B. The virus is transmitted by the bite of an arthropod vector.
    C. The virus proliferates rapidly in infected hosts resulting in a short incubation.
    D. The virus grows readily in cell culture.
    E. The virus readily causes a viremia.

62. A virus was isolated from a nasopharyngeal sample from a 5-month old child in January. The virus produced cytopathogenic
effects of large, refractile syncytia in HEp-2 cells in 5 to 7 days and failed to hemadsorb guinea pig erythrocytes. Which virus is the
most likely candidate?
     A. Measles
    B. Influenza
     C. Respiratory syncytial virus
     D. Parainfluenza
     E. Mumps

63. Macrophages play all of the following roles in antiviral immunity except:
    A. Synthesize gamma interferon
    B. Phagocytize virus particles
    C. Kill virus infected cells
    D. Bind antibodies by the Fc portion of molecule becoming able to kill certain target cells
    E. Process and present viral antigens

64. Interferon plays a number of roles in antiviral immunity except:
     A. Activating macrophages
     B. Interfere with translation of viral proteins
     C. Interfere with cell division
     D. Binds directly to viral proteins resulting in neutralization of viruses
     E. Increase expression of cell surface proteins

65. Antibodies may function in viral immunity via all of the following except:
    A. Agglutinate viral particles
    B. By induction of a RNAase which destroys viral messenger
    C. Help destroy viral infected cells by binding to Fc receptors on NK cells
    D. Interfere with viral uncoating
    E. May function in lysis of enveloped virus in the presence of complement

66. Which of the following diseases is least likely to be caused by adenoviruses?
    A. Pharyngoconjunctival fever
    B. Acute respiratory disease
    C. Encephalitis
    D. Conjunctivitis
    E. Gastroenteritis

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Medical Micro Block #3 – 1996                                                                                             9
Matching question - Match the best response with each question. The same response (letter) can be used more than
once. Questions 67-70.
A. Shift
B. Drift
C. Both
D. Neither

67. Which of the above is/are associated with changes in influenza antigenicity?

68. Which of the above is/are associated with a genetic recombination event?

69. Which of the above is/are responsible for sudden world-wide pandemics?

70. Which of the above can occur after mutation of only 2 amino acids?

Questions 71-73.
A. Prions
B. Viruses
C. Both
D. Neither

71. Frequently cause a cellular immune response which plays a role in recovery

72. May induce large amounts of interferon

74. Which of the following diseases does not belong with the others?
    A. Hydrops faetalis
    B. Fifth disease
    C. Progressive multifocal leucoencephalopathy
    D. Arthritis
    E. Aplastic crisis

75. Which of the following is least likely to represent a mechanism where a virus infection may result in outoimmunity?
    A. Direct lysis of infected cells
    B. Induction of MHC antigens
    C. Exposure of sequestered antigens
    D. Polyclonal B cell activation
    E. Molecular mimicry

76. Which of the following is not a property of polyomavirus?
    A. Circular genome
    B. Double stranded RNA
    C. Icosahedral
    D. Induction of T antigens
    E. Genome may become integrated into host genome

77. Which of the following is not true for human papillomaviruses?
    A. Types 16 and 18 are associated with cervical cancer.
    B. Early genes 6 and 7 (E6 & E7) play a role in oncogenesis.
    C. May be cultured only in human and monkey cells
    D. Replicate only in the outer layers of the skin
    E. May be treated successfully with interferon and certain other chemicals.

78. Tranformation of cells by DNA tumor viruses may result in all of the following except:
    A. Integration of the viral genome
    B. Induction of "T" antigen
    C. Expression of early genes
    D. Binding and/or inactivating anti oncogenes
    E. Lysis of infected cell

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Medical Micro Block #3 – 1996                                                                                                       10
79. All of the following is true of rabiesvirus except:
    A. Viral antigens may be found in the cornea or nape of the neck in advanced cases.
    B. May be transmitted by inhalation
    C. Incubation periods may be 6 months or longer.
    D. Disease may be prevented in man using live virus vaccines.
    E. Death usually follows after overt disease expression.

80. The agent causing Creutzfeldt-Jacob syndrome has all of the following properies except:
    A. May be transmitted to laboratory animals
    B. Remarkable stability to physical and chemical agents
    C. Lack of sensitivity to proteinase K and other protein denaturating agents
    D. May be transmitted man to man
    E. Conversion to the infectious form is always associated with an amino acid change

81. All of the following are true for EBOLA virus except:
    A. Are long and filamentous
    B. Readily transmitted through contaminated body secretions
    C. Monkeys represent the reservoir host.
    D. May result in extensive hemorrhages
    E. Some strains can be transmitted by inhalation.

Questions 82 and 83
A. Rubeola
B. Rubella
C. Both
D. Neither

82. Characterized as a 3 day rash with lymph node involvement.

83. Virus has negative polarity single stranded RNA with polymerase activity.

84. All of the following descriptors correctly describe viruses EXCEPT:
    A. Obligate intracellular parasites
    B. Simply organized entities
    C. Particles devoid of enzymatic activity
    D. Agents refractory to antibiotic treatment
    E. Filterable agents

85. All of the following statements concerning capsomeres of icosahedral viruses are correct EXCEPT:
    A. Capsomeres protect against nuclease destruction of viral genomes.
    B. Capsomeres are morphological building blocks and typically are composed of multiple copies of one or more
         viral gene products.
    C. All capsomeres in a viral capsid may be identical.
    D. Capsomere antigenic determinants of picornaviruses influence species and cell-specific tropisms.
    E. Capsomere antigenic determinants of herpesviruses induce essential neutralizing antibodies.

86. All of the following statements concerning viruses are correct EXCEPT:
    A. Enveloped viruses are more often responsible for giant cell or syncytia formation than naked capsid viruses.
    B. Viruses replicate by a gradual increase in size, followed by division.
    C. A viral genome is composed of either DNA or RNA, but not both.
    D. The adenovirus penton reflects the 5 fold rotational symmetry of the 20 icosahedral capsid vertices.
    E. Either a naked capsid or enveloped capsid may be correctly termed a virion.

87. Some of the orthomyxoviruses and paramyxoviruses that produce little or no cytopathic effect in cell culture can be detected by :
    A. Plaque reduction
    B. Quantal or serial end point assay
    C. Neutralization
    D. Focus formation
    E. Hemadsorption

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Medical Micro Block #3 – 1996                                                                                                   11
89. Dengue virus and Epstein Barr virus could both correctly be described as:
    A. Naked capsid icosahedral viruses
    B. Enveloped icosahedral viruses
    C. DNA viruses
    D. Viruses of complex symmetry
    E. Enveloped helical viruses

90. All of the following viruses are nonenveloped (naked) EXCEPT:
    A. Rotavirus
    B. Coxsackie A16 virus
    C. Polyoma virus
    D. Human papilloma virus type 16
    E. Rabies virus

91. The viral eclipse period is irreversibly initiated with:
    A. Adsorption
    B. Penetration
    C. Uncoating
    D. Genome activation
    E. Maturation (assembly)

92. Post-translational cleavage of large polypeptide molecules is important in the replication strategy of:
    A. Respiratory syncytial virus
    B. Human immunodeficiency virus type 1
    C. Influenza virus
    D. Parainfluenza virus type 1
    E. None of the above

93. All of the following viruses have a virion-associated RNA polymerase EXCEPT:
    A. Vaccinia
    B. Rubeola virus
    C. Influenza
    D. Hepatitis C virus
    E. Respiratory syncytial virus

94. A newly discovered virus has a continuous single-stranded RNA genome. A cDNA (complementary DNA) made from the genome
RNA with a commercially available reverse transcriptase hybridizes with RNA extracted from the polyribosomes of infected cells. All
of the following statements are potentially feasible EXCEPT:
     A. The RNA viral genome encodes an RNA-directed RNApolymerase.
     B. The new isolate displays sero-crossreactivity with known coxsackie A viruses.
     C. RNA-dependent RNA polymerase activity is demonstrated in disrupted virions purified from infected cell
     D. A mouth pipetting accident exposes a laboratory technician to concentrated genomic RNA extracted from purified
          viral particles. Following exposure the technician appears to develope a viral infection which leads to asceptic
     E. Antibody produced against the purified virions of this new isolate precipitated a high molecular weight
          polyprotein precursor from lysates of viral infected cells.

95. All of the following characteristics are associated with hepatitis B virus replication, EXCEPT:
    A. The complete ( + ) strand DNA which exists within the mature Dane particle is transcribed to yield a ( - ) strand
         RNA pregenome.
    B. An RNA pregenome is degraded by RNase H activity.
    C. An RNA pregenome is reverse transcribed by a polymerase with RNA-dependent DNA polymerase activity.
    D. A complete (-) strand DNA is transcribed by a polymerase with DNA-dependent DNA polymerase activity to
         yield a partially double stranded DNA with a complete (-) strand and an incomplete (+) strand.
    E. Immature cores containing HBCAg as well as a complete (-) strand and a partial (+) strand of DNA are enveloped
         by HBSAg by budding through the endoplasmic reticulum.

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Medical Micro Block #3 – 1996                                                                                                           12
96. For an enveloped icosahedral herpes virus, all of the following events in infection are correct,EXCEPT:
    A. Adsorption-------involves electrostatic interaction with cellular receptors.
    B. Penetration-------by fusion with the plasma membrane.
    C. Uncoating---------may involve lysosomes
    D. Maturation--------one segment involves assembly of capsomeres
    E. Release------------involves final maturation by budding from the plasma membrane.

97. Which of the following virus families requires denovo protein synthesis to complete its uncoating process?
    A. Herpesviridae
    B. Papovaviridae
    C. Picornaviridae
    D. Poxviridae
    E. Togaviridae

98. A segmented virus such as a bunyavirus acquires a new glycoprotein peplomer during mixed infection with a different closely
related bunyavirus serotype and this antigenic shift initiates a pandemic. Which of the following terms is the most likely explanation
for this phenomenon?
     A. Phenotypic masking
     B. Genetic reassortment
     C. Phenotypic mixing
     D. Complementation
     E. Intragenic recombination

99. All of the following statements concerning phenotypic mixing or phenotypic masking are correct, EXCEPT:
    A. Phenotypic mixing is a form of viral complementation.
    B. Phenotypic mixing may alter the antibody neutralization profile of progeny virions.
    C. Phenotypic mixing results in a stable and permanent change in the progeny viral genomes.
    D. Phenotypic mixing is most likely to occur between closely related viruses.
    E. Phenotypic masking of one naked capsid icosahedral virus by a second virus of similar morphology is analogous
         to pseudotype formation between two different enveloped viruses.

Case study which applies to the next questions 100-101. You are presented with an elderly patient in his 90s who has recently been put
on a glucocorticoid regimen of prednisone to treat a rather sudden onset of severe rheumatoid arthritis. However, the patient seems to
have a second problem exemplified by the following symptoms: 1) the patient has a general malaise and a specific tingling or nerve
sensation in the right side of her face; (2) the patient experiences occasional shooting pains in the right side of the face or head that
appear associated with the dermatome of the trigeminal ganglion; (3) the patient has a watery right eye and partially closed right eye
lid; (4) on the right side of the nose and just above the right eye you notice that the skin is white, raised, broken, and wet in two spots
suggestive of either bug bites or broken viral vesicles; (5) the putative viral vesicles are localized on the right side of the face and no
lesions are noted on the left side of the face; (6) the patient has no other vesicles on her body and has not suffered from labialis or
genital herpes within the past 10 years; (6) the patient has been staying alone and has not been in contact with anyone who potentially
had pink eye or an active viral infection of any kind; (7) the patient has not been ever operated on and has received no blood

100. Which of the following virus infections is the best diagnosis of this patientÕs new health problem?
    A. Cytomegalovirus
    B. Adenovirus
    C. Herpes simplex type 1
    D. Human immunodeficiency virus type 1
    E. Varicella-zoster virus

101. Which of the following drug or treatment strategies is correct for the above patient?
    A. Give antibiotic eye drops alone. There is no antiviral drug for adenovirus pink eye.
    B. Give antibiotic eye drops and topical IUDR for Herpes keratoconjunctivitis.
    C. Give antibiotic eye drops and take a wait and see approach. Utilize low dose acyclovir (Zovirax) (100 mg two
        times per day) if the condition of the eye worsens.
    D. Give antibiotic eye drops and immediately administer one of the following 3 drugs: foscarnet, ganciclovir or
        zidovudine (AZT).
    E. Give antibiotic eye drops and immediately administer high dose acyclovir (Zovirax) (up to 800 mg five times per

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Medical Micro Block #3 – 1996                                                                                                         13
Use the following choices (A-E) to answer questions 102-106. Indicate the one lettered heading that is most closely associated with
each numbered descriptor.
A. Cytomegalovirus
B. Epstein Barr virus
C. Herpes simplex type 2
D. Human herpes virus 6
E. Molluscum contagiosum virus

102. A sexually transmitted poxvirus responsible for multiple pearly white nodules in the epidermis.

103. An infant rash referred to as Exanthem subitum

104. Neonatal encephalitis following birth canal infection which is treated with systemic acyclovir (Zovirax).

105. An infection of B lymphocytes which induces lymphoma in a percentage of previously infected immunosuppressed AIDS

106. A heterophile-negative mononucleosis which is transmitted sexually, in saliva and urine, and by leukocyte transfusion.

107. Hepatitis E virus and hepatitis A virus are most often transmitted by:
    A. Blood transfusion
    B. Food and/or water
    C. Sexual contact
    D. Shared needles
    E. Airborne droplets

108. All of the following statements about hepatitis B virus are correct, EXCEPT:
    A. Chronic carriers with HBeAg (+) blood have increased infectivity and increased potential for active liver disease.
    B. An attenuated live virus vaccine named recombivax (Merck) is recommended for protection of newborns of
         HBsAg (+) mothers.
    C. HBsAg is a useful early diagnostic marker of HBV infection in blood during the long incubation period infections.
    E. Hepatitis B virus may be transmitted by exposure to blood during patient care, saliva, sharing needles and sexual

109. All of the following statements about Hepatitis A virus are correct, EXCEPT:
    A. Hepatitis A virus is most contageous just before icterus (fever) and has a high secondary attack rate within
         households and crowded institutions.
    B. Current hepatitis A virus infection is indicated by the presence of anti-HAAg IgM in blood.
    C. Havrix, a newly licensed inactivated viral vaccine, is now recommended for HAV post-exposure; thus replacing
         ineffective treatments with immune serum globulin (ISG).
    D. Hepatitis A virus in the USA causes the greatest percentage of acute infections but does not typically cause the
         chronic carrier state, chronic active liver disease, cirrhosis, or primary hepatic carcinoma.
    E. Hepatitis A virus and Hepatitis C virus both lack virion-associated polymerases and are single stranded RNA

110. All of the following statements regarding Salk and Sabin polio vaccines are correct, EXCEPT:
    A. Salk vaccine induces systemic humoral IgG protection against CNS disease.
    B. Salk vaccine rather than Sabin vaccine is recommended for nonimmune adults and high risk immunocompromised
    C. Salk vaccine replicates in the gut preventing subsequent infection by wild type virulent polio and its shed in feces
         helps to prevent epidemic spread in the community.
    D. Sabin vaccine induces duodenal and nasal secretory IgA protection better than Salk vaccine.
    E. Childhood vaccination recommendations now indicate that Salk vaccine be administered first to protect against
         any adverse effects of the Sabin vaccine which is given subsequently.

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Medical Micro Block #3 – 1996                                                                                                    14
111. Epidemic pleurodynia (Bornholm disease) and myocarditis both are caused by:
    A. Coxsackie A viruses
    B. Coxsackie B viruses
    C. Polio viruses
    D. Reoviruses
    E. Echo viruses

112. Which of the following manifestations is MOST typical (common) to all of the following viral groups: 1) polio viruses; 2)
coxsackie A viruses; 3) coxsackie B viruses; and 4) echo viruses?
    A. Herpangina
    B. Paralytic disease
    C. URT rhinitis
    D. Asceptic meningitis
    E. Hand-foot-and-mouth disease

113. The current standard of care in HIV-1 antiretroviral therapy consists of:
    A. Prophylaxis of opportunistic infections while deferring antiretroviral therapy
    B. Serial, rotating nucleoside analog monotherapy
    C. Combinations of multiple protease inhibitors
    D.Combination therapy consisting of multiple nucleoside analogues or two nucleoside analogues and a protease
    E. None of the above.

114. Viral load as measured by bDNA test in advanced AIDS patients has been reduced below detectable levels (<500copies/mL) with
    A. Eighteen months of zidovudine (AZT) monotherapy
    B. Trimethoprim-sulfamethoxazole combined with zidovudine (AZT)
    C. Triple therapy with indinavir (Crixivan), zidovudine (AZT), and lamivudine (3TC).
    D. Lamivudine (3TC) and zidovudine (AZT) alternating monotherapy.
    E. All of the above

115. AIDS patients who have taken lamivudine (3TC) and zidovudine (AZT) for an extended period of time who begin to show
significant viral load increase in plasma should
    A. Discontinue 3TC and AZT and switch to a combination of protease inhibitors (indinavir and saquinavir or
    B. Increase the dosage of 3TC and AZT
    C. Discontinue 3TC and AZT and switch to videx (ddI) and zerit (d4T) if tolerated
    D. Continue 3TC and AZT at current dosage and add indinavir (Crixivan)
    E. Two of the above approaches are rational given our present knowledge

116. Nonbacterial infantile diarrhea is strongly associated with
    A. Human reovirus infections
    B. Human rotavirus infections
    C. Norwalk agent infections
    D. Adenovirus infections
    E. La Crosse agent infections

118. All of the following statements are correct, EXCEPT:
    A. Lymphocytic choriomeningitis virus (LCM), a flavivirus, persistently infects mice, is a relative of dengue fever
         virus, but unlike Dengue fever virus it does not illicit symptoms in man.
    B. Rotaviruses have a double-stranded segmented RNA genome and a virion-associated RNA dependent RNA
    C. The Norwalk agent, a calicivirus, causes diarrhea predominately in young adolescents or adults.
    D. Human reoviruses are strong inducers of interferon.
    E. Coronaviruses are +stranded RNA viruses, associated with common colds, and noted for their inability to illicit a
         lasting immune response.

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Medical Micro Block #3 – 1996                                                                                              15
119. All of the following statements concerning AIDS or its associated retrovirus, human immunodeficiency virus (HIV-1),
are correct, EXCEPT:
     A. Pneumocystis carinii pneumonia is a common frequent indicator infection for AIDS.
     B. A decline in anti-p24 antibody often is diagnostic of progression to terminal stage or frank AIDS.
     C. Viral neutralizing antibodies in patient blood are not indicative of protection against HIV-1 induced disease.
     D. The T4/T8 ratio is >1 in AIDS patients.
     E. Decreased mitogen response to PHA and decreased IL-2 production are typically associated with the development
         of AIDS.

120. All of the following statements pertaining to oncogenes present in retroviral genomes (v-oncs) are correct, EXCEPT:
    A. A combination of recombination and mutational events were involved in generating v-oncs from cellular
    B. These v-oncs are typically found in the genomes of endogenous retroviruses.
    C. Expression of these v-oncs acutely transforms normal cells to produce transformed cells with enhanced growth
         and/or tumorigenic potential.
    D. These oncogenes typically encode altered homologues of normal cellular growth control genes which are highly
         conserved in many species.
    E. These oncogenes are most often present in replication defective viruses.

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Medical Micro Block #3 – 1996                                                            16
                                                       Answers to Micro Block 3 - 1996

1. C                                                                      69. A
2. E                                                                      70. B
3. C                                                                      71. B
4. C                                                                      74. C
5. A                                                                      75. A
6. D                                                                      76. B
7. A                                                                      77. C
8. C                                                                      78. E
9. B                                                                      79. D
10. D                                                                     80. E
11. D                                                                     81. C
12. A                                                                     82. B
13. D                                                                     83. A
14. E                                                                     84. C
15. D                                                                     85. E
16. D                                                                     86. B
17. A                                                                     87. E
18. A                                                                     89. B
19. B                                                                     90. E
20. B                                                                     91. C
21. D                                                                     92. B
22. C                                                                     93. D
23. B                                                                     94. C
24. B                                                                     95. A
25. A                                                                     96. E
26. B                                                                     97. D
27. A                                                                     98. B
29. E                                                                     99. C
30. D                                                                     100. E
31. B                                                                     101. E
32. A                                                                     102. E
33. C                                                                     103. D
34. B                                                                     104. C
35. A                                                                     105. B
36. D                                                                     106. A
37. D                                                                     107. B
38. D                                                                     108. B
40. C                                                                     109. C
41. B                                                                     110. C
42. A                                                                     111. B
43. E                                                                     112. D
45. D                                                                     113. D
46. C                                                                     114. C
47. E                                                                     115. E
48. C                                                                     116. B
49. C                                                                     118. A
50. D                                                                     119. D
51. E                                                                     120. B
52. D
53. D
54. B
56. C
57. A
58. B
59. D
60. C
61. D
62. C
63. A
64. D
65. B
66. C
67. C
68. A
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